ITU-T defines Optical Transport Network (OTN) as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, routing, management, supervision and survivability of optical channels carrying client signals. Of note, OTN is defined in: ITU-T G.709 “Interfaces for the optical transport network (OTN)”; ITU-T G.798 “Characteristics of optical transport network hierarchy equipment functional blocks”; OTN Standard FEC (Called GFEC sometimes) is defined in ITU-T G.975; OTN Jitter is defined in ITU-T G.8251 “The control of jitter and wander within the optical transport network (OTN)”; ITU-T G.870 “Terms and definitions for Optical Transport Networks (OTN)”; ITU-T G.871 “Framework for optical transport network Recommendations”; ITU-T G.873.1 “Optical Transport Network (OTN): Linear protection”; ITU-T G.874 “Management aspects of the optical transport network element”; ITU-T G.874.1 “Optical transport network (OTN): Protocol-neutral management information model for the network element view”; ITU-T G.959.1 “Optical transport network physical layer interfaces”; and ITU-T G.8201 “Error performance parameters and objectives for multi-operator international paths within the Optical Transport Network (OTN)”.
Disadvantageously, OTN provides for full transparency only with telecom signals, and not with datacom signals, such as 10 Gigabit Ethernet (10 GBE), 10 Gigabit Fibre Chanel (10 GFC), future 100 Gigabit Ethernet (100 GBE), and the like. Transport carriers, such as long-haul providers, prefer 100% bit transparent transport of datacom signals for various reasons. For instance, transparent transport provides simpler provisioning providing a connection that emulates fiber. Another reason is that some routers use the preamble and 64 B/66 B code words for proprietary control and data channels and dropping those bits disrupts router-to-router communications.